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Re: my token about the "3 or more layer" structure for the ontology

From: Ruben Tous \(UPC\) <rtous@ac.upc.edu>
Date: Mon, 24 Nov 2008 13:28:47 +0100
Message-ID: <00cb01c94e30$35a21060$2f225393@UPCNET1757BE22>
To: "Pierre-Antoine Champin" <pchampin@liris.cnrs.fr>, "Felix Sasaki" <fsasaki@w3.org>
Cc: <public-media-annotation@w3.org>

Hi Pierre-Antoine, Felix, all,

after the feedback from Felix in 
http://lists.w3.org/Archives/Public/public-media-annotation/2008Nov/0115.html I 
see that my understanding of the approach has been slightly biased till now 
(is my fault for having arrived late). I also took for granted that we would 
formalise an explicit reference format, but now I realize that this is not 
strictly necessary. I’ve added a new entry at the top of the features table 
(http://www.w3.org/2008/WebVideo/Annotations/wiki/FeaturesTable) because I 
think that this aspect has an important impact on the other features.

Best regards,


----- Original Message ----- 
From: "Pierre-Antoine Champin" <pchampin@liris.cnrs.fr>
To: "Felix Sasaki" <fsasaki@w3.org>
Cc: <public-media-annotation@w3.org>
Sent: Monday, November 24, 2008 12:47 PM
Subject: Re: my token about the "3 or more layer" structure for the ontology

Hi Felix, thank you for your feedback.

First, the term "data structure" was a bad choice. I should have written
"conceptual model", which describes better what I am interested in. I
think once we agree on a conceptual model, we can chose the best syntax
to represent it -- if we want to...

As a matter of fact, I took for granted that we would have to define our
own format. But once again, the most important thing is the conceptual

To be clear about my idea of a "conceptual model" or "ontology"... It
does not necessarily implies that we describe it formally. You advocate
a "prose" description, and it is indeed a possibility, as long as it is
precise enough.

However, that does not rule out, IMHO, the discussion about structure --
and I still think structure is important for interoperability problems.
I take an example:

ID3 [1] has apparently a flat structure: it is a list of properties with
text value. However, take the descriptions of the following properties:

>   TALB
>    The 'Album/Movie/Show title' frame is intended for the title of the
>    recording (or source of sound) from which the audio in the file is
>    taken.
>   TOAL
>    The 'Original album/movie/show title' frame is intended for the title
>    of the original recording (or source of sound), if for example the
>    music in the file should be a cover of a previously released song.

There is an awful lot of structure hidden in those flat properties!
A sound file is *taken from* a *recording*, which has a *title* and can
be an *album*, a *movie*, a *show* (and the list is probably not
intended to be exhaustive). But it can have been *previously released*
in another *recording*.

So mapping those properties to, say, Dublin Core properties, not only
requires to find an equivalence between the notion title, but also
*taken from* (dc:source ?), *previously released* (??), etc...


[1] http://www.id3.org/id3v2.4.0-frames

Felix Sasaki a écrit :
> Hello Pierre-Antoine,
> Pierre-Antoine Champin さんは書きました:
>> Felix,
>> although I participated in putting the debate in terms of "XML vs. RDF",
>> my concern was not about a precise syntax or foramt, and I agree with
>> you that it should not be.
> Just for clarification: "agree that it should not be" means "we do not
> need to define a syntax" or "we should not discuss XML vs. RDF, but need
> to decide on a syntax"? If the latter, which syntax do you propose?
>> However in my view the question is more fundamental. Let me reword it.
>> Designing an ontology involves, IMHO, a trade-off between faithfully
>> representing the domain of interest, and projecting it in a practical
>> data structure.
> Maybe here we already have different opinions: I think we can design an
> ontology without a practical data structure. The current API / ontology
> proposal does just that: defining a list of terms *as prose*. The data
> structure related parts are only in the API, and in the prose mapping
> descriptions.
>> Failthful in our context means:
>> - able to cover a large part of legacy metadata
>>   - able to satisfy most of the requirements of our use cases
>> Practical in our context, means that the ontology should be:
>> - easy to use by media publisher
>> - easy to implement in browsers
>> A very easy to use and implement data structure is a list of
>> (attribute,value) pairs -- the so-called "flat" structure.
>> By the way, even easier is a list of simple tags -- which can be tweaked
>> into (attribute,value) pairs anyway, as pointed out by your previous
>> mail about flickr.
>> However, I think that this is too much of a simplification:
>> - it does not satisfy come requirements (like the multi-level or
>> collection) -- though we might decide that those ones are too complex
>> - my intuition is that more structure would make "impedence mismatch"
>> between legacy vocabularies easier to point out and solve
> I agree that this simplification does not cover many use cases like
> "multi-level  or collection". But I also think for this version (1.0 of
> the ontology / API) we should concentrate on the simple approach which
> is important for all use cases and application scenarios. If that founds
> adoption, we can shoot for 2.0 and a more complex approach.
> Btw., of course we have not described all application scenarios, use
> cases and requirements yet. Nevertheless I think that the requirement to
> get information across heterogenous formats is central to our WG.
> I don't think that more or less structure is related to the quality of
> mapping between different vocabularies. For this mapping, detailed
> knowledge brought in by the WG parcitipants about these vocabularies is
> mostly important. If the mapping then is represented in prose, or as
> more or less structured XML or RDF, is not important IMO. However, I do
> think that a detailed prose description is important for the API, and it
> can also help understanding a structured representation, if we decide to
> do that.
> Felix
>>   pa
>> Felix Sasaki a écrit :
>>> Ruben Tous (UPC) さんは書きました:
>>>> Hi Pierre-Antoine, Silvia, all,
>>>> I think that normalisation/denormalisation is related to the more
>>>> general discussion about structured*/flat annotations (handling
>>>> events, agents, etc. as separated structures) . The multi-level
>>>> description discussion is probably a sub-topic within that general
>>>> one, and refers only (as I've understood till now) to splitting
>>>> (normalising) the main structure (the one describing the digital
>>>> object) into several entities but only regarding different abstraction
>>>> levels (e.g. document and instance).
>>>> So, probably we should decide first about the structured*/flat
>>>> question. If we choose "flat", then we could maybe discard also the
>>>> multi-level description.
>>>> Probably, there's a latent high-level question behind this discussion:
>>>> will the ontology model the way annotations are interchanged, or will
>>>> it model their underlying semantic grounding?
>>>> Best regards,
>>>> Ruben
>>>> *When talking about structured annotations I'm not just referring to
>>>> hierarchycal ones (XML), I refer to annotations with ObjectProperties
>>>> (inlined or linked within the same annotation) (e.g. RDF).
>>> Reading this discussion and the "features" wiki page, the "data model
>>> rows", I have the impression that there is some tension between using
>>> XML and RDF. I can understand that tension, but I think we should not
>>> spend time on discussing it in this group. Nevertheless, it lets me more
>>> and more think that we should not be format specific in our ontology,
>>> but use just a prose description as the normative outcome, that is in
>>> the "Ontology 1.0" Recommendation. If people want to write non-normative
>>> RDF- and XML-formats, they are free to do so. I think we should focus on
>>> formulating the terminology in the prose in a way that that makes a
>>> formalization in whatever format straightforward.
>>> Felix
>>>> ----- Original Message ----- From: "Silvia Pfeiffer"
>>>> <silviapfeiffer1@gmail.com>
>>>> To: "Ruben Tous (UPC)" <rtous@ac.upc.edu>
>>>> Cc: <public-media-annotation@w3.org>
>>>> Sent: Wednesday, November 19, 2008 10:10 PM
>>>> Subject: Re: my token about the "3 or more layer" structure for the
>>>> ontology
>>>> Hi Ruben,
>>>> It is always a matter of use cases.
>>>> When we talk about management of collections, there will be overlap
>>>> between the annotations of different files, which can be handled more
>>>> efficiently (in a database sense: normalise your schema).
>>>> However, if you receive an individual media resource, you want all of
>>>> its annotations to be available with the media resource, i.e. you want
>>>> an "intelligent" media object that can tell you things about itself.
>>>> I don't see these things as separate. Let's take a real-world example.
>>>> Let's assume I have a Web server with thousands of videos. They fall
>>>> into categories and within categories into event, where each video
>>>> within an event has the same metadata about the event. On the server,
>>>> I would store the metadata in a database. I would do normalisation of
>>>> the data and just store the data for each event once, but have a
>>>> relationship table for video-event-relationships. Now, a Web Browser
>>>> requests one of the videos for playback (or a search engine comes
>>>> along and asks about the metadata for a video). Of course, I go ahead
>>>> and extract all related metadata about that video from the database
>>>> and send it with the video (or in the case of the search engine:
>>>> without the video). I further have two ways of sending the metadata: I
>>>> can send it in a text file (which is probably all the search engine
>>>> needs), or I can send it multiplexed into the video file, e.g. as a
>>>> metadata header (e.g. MP3 has ID3 for this, Ogg has vorbiscomment,
>>>> other file formats have different metadata headers).
>>>> I don't think we need to overly concern ourselves with whether we
>>>> normalise our data structure. This is an "implementation" issue. We
>>>> should understand the general way in which metadata is being handled
>>>> as in the example above and not create schemas that won't work in this
>>>> and other scenarios. But we should focus on identifying which
>>>> information is important to keep about a video or audio file.
>>>> Cheers,
>>>> Silvia.
>>>> On Thu, Nov 20, 2008 at 12:01 AM, Ruben Tous (UPC) <rtous@ac.upc.edu>
>>>> wrote:
>>>>> Dear Véronique, Silvia, all,
>>>>> I agree with both of you in that the need of multiple description
>>>>> levels is
>>>>> only related to a small subset of use cases, basically to those
>>>>> related to
>>>>> the management of groups of resources (e.g. digital asset management
>>>>> systems, user media collections, etc.). Instead, we are (I guess)
>>>>> focused in
>>>>> embedded annotations in individual resources.
>>>>> However, I think that there are solutions which cover both cases, the
>>>>> simple
>>>>> and the complex one. For instance, we could embed the following
>>>>> annotation
>>>>> within an MPEG video:
>>>>> <mawg:Video rdf:ID=http://example.org/video/01">
>>>>> <mawg:title>astronaut loses tool bag during spacewalk </mawg:title>
>>>>> <mawg:creator>John Smith</mawg:creator>
>>>>> </mawg:Video>
>>>>> <mawg:Resource rdf:ID="http://example.org/resource/01">
>>>>> <mawg:format>FLV</mawg:format>
>>>>> <mawg:filesize>21342342</mawg:filesize>
>>>>> <mawg:duration>PT1004199059S</mawg:duration>
>>>>> </ mawg:videoID rdf:resource="http://example.org/video/01">
>>>>> </mawg:Resource>
>>>>> It is structured and it offers 2 abstraction levels, but it can be
>>>>> serialized like a plain record. When appearing in isolated resources,
>>>>> the
>>>>> high-level annotation ("Video" in this case) would be repeated. When
>>>>> appearing within a collection's annotation the "Video" annotation
>>>>> would
>>>>> appear just once.
>>>>> It is not so different than in XMP. Take to the following XMP
>>>>> example...
>>>>> http://www.w3.org/2008/WebVideo/Annotations/wiki/images/8/8a/Xmp_example.xml
>>>>> Best regards,
>>>>> Ruben
>>>>> ----- Original Message ----- From: <vmalaise@few.vu.nl>
>>>>> To: <public-media-annotation@w3.org>
>>>>> Sent: Wednesday, November 19, 2008 11:27 AM
>>>>> Subject: my token about the "3 or more layer" structure for the
>>>>> ontology
>>>>>> Hi everyone,
>>>>>> I was at first very much in favor of an ontology that would
>>>>>> distinguish
>>>>>> different levels of media documents, like
>>>>>> "work-manifestation-instance-item",
>>>>>> but after reading this email from the list:
>>>>>> http://lists.w3.org/Archives/Public/public-media-annotation/2008Nov/0076.html
>>>>>> I agreed with the fact that we would probably only need a simple
>>>>>> structure
>>>>>> in
>>>>>> our case, that multi-level structures were meant for linking
>>>>>> different
>>>>>> entities
>>>>>> that have different status together: if we aim for linking the
>>>>>> descriptions of a
>>>>>> single item between different vocabularies, we need to specify if the
>>>>>> single
>>>>>> item is a work_in_XX_vocabulary, more likely a
>>>>>> manifestation_in_XX_vocabulary
>>>>>> (see note 1 below), to give its "type", and if people/use cases
>>>>>> want to
>>>>>> link
>>>>>> this single item to other related works, manifestations, instances or
>>>>>> items,
>>>>>> they can use the framework defined in the schemas reviewed in
>>>>>> http://www.w3.org/2008/WebVideo/Annotations/wiki/MultilevelDescriptionReview
>>>>>> and use these properties for completing their description.
>>>>>> So we would need a property like "has_type" to link a single
>>>>>> description's
>>>>>> identifier to the correct level of multilevel description schemes.
>>>>>> I changed my mind think that only one "family" of use cases would
>>>>>> need
>>>>>> more
>>>>>> levels, that they are somehow context dependent (and could thus be
>>>>>> considered as
>>>>>> requirements for a family of use cases), but of course if it turns
>>>>>> out
>>>>>> that more
>>>>>> that one family of use cases needs this distinction, then we should
>>>>>> consider
>>>>>> going for a multilevel structure. Anyway, we would need to map
>>>>>> informally
>>>>>> the
>>>>>> way these levels are expressed, in order to provide possible relevant
>>>>>> "types"
>>>>>> for the description of each single element.
>>>>>> note 1: by specifying the different names of the relevant
>>>>>> Concepts/terms
>>>>>> in
>>>>>> schemes like VRA, XMP etc., we would informally define a semantic
>>>>>> equivalence
>>>>>> between the ways these schema express these levels of description. It
>>>>>> would look
>>>>>> like:
>>>>>> <metadataFile>
>>>>>> <id="identifier">
>>>>>> <hasType xmpMM:InstanceID, vra:image, frbr:item>
>>>>>> </metadataFile>
>>>>>> I think that the table
>>>>>> http://www.w3.org/2008/WebVideo/Annotations/wiki/FeaturesTable
>>>>>> is a very valuable tool for people to express their ideas about it,
>>>>>> thank
>>>>>> you
>>>>>> very much Ruben for designing it!
>>>>>> Best regards,
>>>>>> Véronique
Received on Monday, 24 November 2008 12:32:45 UTC

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